The era of commercial space travel is upon us, and if NASA's Apollo missions are any precedent, it will likely become routine as the initial excitement fades. Interest in space will wax and wane.

You couldn't escape the hubbub when SpaceX's Dragon spacecraft launched in May - my colleagues at SmartPlanet fired off a steady succession of articles. A commercial spacecraft linking up with the International Space Station (ISS) is absolutely novel in the wake of the space race and U.S. shuttle's renowned run of service.

The Dragon is now tentatively scheduled to lift off for its second unmanned space flight in October - with many to follow. SpaceX earned NASA's stamp of approval to run its cargo missions, and will triumphantly fulfill its service contract with the agency. The public will also be much less tuned in by then.

NASA was at the height of its popularity in the late 1960's as the world witnessed its crowning achievement: the 1969 Apollo moon landing. Space was a big deal - both politically and socially - but then public interest began to wane with each succeeding mission. NASA only experienced a brief comeback during the 1980's.

It's not fair to single out SpaceX, because there's plenty of other examples. NASA's Curiosity rover has been eclipsed by the iPhone 5 launch. And I doubt that launching billionaires into space for kicks, which many other private enterprise aim to do, will prove terribly popular these days.

Could Musk and SpaceX pull off a comeback? Sure, and I hope that he and his team do. SpaceX's inspirations stretch all the way to Mars and human colonization of space. Musk has stated that his goal is to make trips to mars as affordable as buying a house, and that's a remarkable vision. Visions just aren't always shared.

Government contracts sustain commercial space travel for the time being, but a key difference is that NASA has had the Federal government's checkbook and wherewithal to stick it out for decades. We'll mine the poles bare before we harvest asteroids or take other commercial activity into space and off the drawing board.

Will private investors be as patient if business goals fall much closer down to Earth? Probably not - unless there's suddenly a sustained sense of urgency to back it all up.